Pulse radiolysis studies of solvent radical cations in liquid 1,2-dichloroethane

Transient absorption spectra with maxima at 270 and 550 nm were observed in liquid pure 1,2-dichloroethane by means of ps and ns pulse radiolysis. The broad absorption band with a maximum around 550 nm decayed according to a first-order reaction with t1/2 = 0.2 ns in ps pulse radiolysis and t1/2 = 200 ns in ns pulse radiolysis. These short lived species were attributed to solvent cations on the basis of scavenger experiments. The slowly decaying species with t1/2 = 1.2μs which absorbs around 400 nm superimposed on the 550 nm band, was tentatively assigned to carbocations. The 270 nm band formed during and after the electron pulse decayed over several microseconds by second-order kinetics. Those radicals which were produced by the dissociative electron attachment to the solvent and by the reaction of cations were responsible for this UV band. (author)